Sentra B13 strange knoking :(

[cpcarranza]

Hello, everyone I'm newbie and new at the site..

I realy hope you can help me, thanks in advance...

I have a misterious sound problem with my car and no one knows around here what it is, my car is:

Sentra XE 1996 B13 GA16DE Manual transmission

The conditions on when the sound shows up are: 1.- when the car is moving slowly and the wheel goes up and down on irregular streets let's say I'm moving at 10-20 km/h in first or second gear on a very damaged street; on that conditions I can hear how the wheel (wheel, axle or differential) moves up and down like something loose or ungrease, but I've taken the car to check tie rods, struts, shock absorbers, brakes, etc. and no one finds that sound

2.- let's say now that I'm moving very slowly in second gear like at 750 rpm and I start to push the pedal, since the engine tries to move and has a load a knocking shows up, NOT Engine knocking (at least I think since at high rpm's never shows), also when changing gears from first to second when I almost release completely the clutch pedal, I think since the engine receives the whole load of the vehicle.

3.- this is like the above but in different condition, let´s say I'm driving in second gear and I have to slow down (to park or get on the street for the garage) and let's say I don't touch the clutch pedal, so I start to push the brake pedal and the rpm's went down to 300-450 rpm's; in this case the same knocking problem appears..., I also checked and replace a motor mount under the battery but the knocking still shows up.

According to me the knocking always appear when I put more load on the engine, since when normal driving it never shows up.

Yesterday I put the car on jack-stands and start the engine, shift second gear and went under the car and ask my wife to push the brake pedal so the rpm's went down to 300-450 and the engine start to shake; so when under the car I found that sometimes the left wheel stopped and the right one still was running, other times vice-verse, I also found that the shock-absorbers were shaking a little since the tires were not on the ground, also the klaxon was hitting with his rear bolt on metal, but none of those sounds were the one I heard, in certain point I think the transmission made a sound ¿lack of oil? I don't think, two weeks ago the dealer change the right oil-seal on the transmission and the right boot on the wheel, so what other thing could this be...

I'm thinking may be the axle or transmission, but what other things can cause this knocking or how do I check this parts...

Thanks in advance and have a nice day...

[SmithSR]

A couple easy things to have a shop look for.

Broken / worn motor mount.Strut mounts (bearing plate) gone bad.Struts blown and not slowing the motion of the spring.

any one or any combination could cause the shaking and knocking.

A shop could diagnose your problem in 5 mins or less, i'll bet.

[cpcarranza]

Thanks SR_Smith

By the way the RPM's that I used in the test were 550-650 rpm's, and the sound appears to me like something spinning..., I guess...

Let's see if I understand...., if I'm wrong please tell me.

"Broken / worn motor mount.": acoording to the Nissan dealer here in Mexico I had a broken (only one) front transmission mount (the one under the battery). So I went to a shop and fix it; the right mount is ok and the rear bottom one looks gray but not broken at all and still flexible, and the front bottom mount isn't broken (I'd really like it was only the mounts, they are cheap :P) I had also replaced the right transverse link mount.

"Strut mounts (bearing plate)": I don't know if this could be the cause, the struts were changed 3 months ago at Michellin's (any how I will make them check it) ALSO when I was under the car with the engine running and my wife pushing the brake pedal I certanly heard a light "stumble" at the struts, but I consider it was noticable and normal since I was pretty close and the wheel were in the air, any way, that's not the sound, but will check the bearings too

"Struts blown and not slowing the motion of the spring": Actually I drive fast (not irresponsable) but I don't think that I might blown them in three months, last Saturday I went to another Michellin's dealer and only told I had a sound that might be in the suspension so they pushed downward the car to the flor and found no sound at the struts, also he went under the car (he was in the pit used for aligment of the toe in) and checked the tie-rod, stabilizer bar, connecting rods, and the stuff releted to them..., and didn't found nothing; on the other hand a week ago the right transverse link mount was replace at Continetal's dealer and he also checked the same stuff and found nothing....

A month ago I went to the brake-shop and told them a had a sound in the brakes (actually a small sound) so they changed the caliper's clips, but didn't found anything else.

After I had replaced the struts, caliper's clips, checked the suspension stuff the NISSAN dealer told me the same the last time I went for servise.... I had:

1.- bad struts (4) they were already replaced.2.- bad steering box works fine, only leaks at pump and container, and bad lower joint.3.- bad transmission mount recently replaced.4.- bad front crank seal recently replaced.5.- bad shift oil-seal at transmission not replaced yet.6.- bad right axle oil seal replaced at Nissan dealer.7.- bad right boot on wheel replaced at Nissan dealer.8.- tie-rods inner and outter not replace since Continental and Michellin dealers say they all are ok.

The last owner was my wife's uncle, and I've been told that he hit a rock on the hi-way, but actually I don't know wich wheel it was....

If you ask me I think is the right axle, if posible I'll record the sound

I really feel bad that this good looking car sounds so terrible, it's like something was broken, people hears it and look at the car...

I would be really glad if some one can help me.

Thanks in advance for your time.

Modified by cpcarranza at 10:02 AM 3/14/2006
Modified by cpcarranza at 10:15 AM 3/14/2006

[SmithSR]

The driveshafts are a shraightforward job. If you think that might be the cause, start throwing more money at that fine little car!

The strut mounts(they are metal plates with a bearing in them) are the culprit of a lot of unusual noises. If you've ruled this out, then have your shop check and recheck the wheel bearings and consider swapping out the cv shafts. It's not complicated on your car, so that's a plus.

[cpcarranza]

Hi, SR_Smith

Do you remember: "A shop could diagnose your problem in 5 mins or less, i'll bet."?

Well I went to a shop today and we were checking the car for half and hour, the man said maybe a screw in the center mamber, so he replaced the screw, and nothing, so the man said he didn't know and that he want to check the car, all parts one by one, tomorrow from 8am-01pm. ; last week I was with a nissan shop and the guy tought it was the left motor mount, so he replaced it, but no changes in the sound...; both of them say that it's not the axle or wheel bearings nor transmission (according to them)..., but they don't know what it might be...

This problem is being very anoying, today I made a recording in a digital recorder and I will try to put it here, so far as I find the cable for this...; I made a record from inside the car and another from the outter with the car moving and making the knocking/rattling sound...

I hope I can find the problem and I hope someone can help me.

Thanks...

[cpcarranza]

Hello, SR_Smith

I recently made a record for the knocking, the file Inside.wav was recorded from inside the car on the pasenger's seat and the Outside.wav was recorded from the outside of the car at the right wheel, both of them were recorden when driving in second gear and pushing the brake pedal so the rpm's lower to 450-500

Do you think this might be the driveshaft?

Modified by cpcarranza at 6:50 AM 3/20/2006
Modified by cpcarranza at 9:03 AM 3/22/2006

[cpcarranza]

Both files were converted by the "Sound Recorder"; just in case you can't open them... Thanks in advance...
Modified by cpcarranza at 9:01 AM 3/22/2006

[cpcarranza]

I will be very glad if someone can give me an advise about this....

Since the recording was very bad I made a new record that's much better than the two last ones.

This recording was made from inside the car when driving in second gear and you can hear the knocking/rattling.

Thanks in advance to everyone.